Rugby league commentator Warren Ryan has resigned from the ABC after being stood down pending an investigation into allegations he made racist remarks on air.

Ryan and colleague David Morrow were suspended last month after a reference made on air by Ryan during the broadcast of a match between the Sydney Roosters and Canterbury Bulldogs.

The ABC asked both men to submit a formal response as part of its investigation.

Ryan, 73, told Fairfax he had written a letter of resignation outlining the reasons for quitting.

However, a spokesman for the ABC said it was yet to receive the letter and was not making any further comment.

The former premiership-winning coach and first grade rugby league player said he would not be apologising for the remark.

"The ABC has suspended me pending an investigation, so I have resigned to save them the trouble of conducting it," he told Fairfax.

"As for the injustice done to David Morrow in standing him down, he wasn't even listening when I was comparing a blow-up on the field between the ref and a player to a scene in the film Gone With The Wind.

"David was busy retrieving other sports results from his smartphone. He only rejoined the commentary as I finished describing the humorous movie scene.

"The word used to describe the character was a direct quote from the film. There was no offence intended, so I won't be apologising. It would be insincere.

"Furthermore, there is no appeasing those who are determined to be offended. So that's it. I've had a long run and, for the most part, it's been very enjoyable. In effect, I've brought forward my intended end-of-season retirement date."

But chairwoman of the Australian Rugby League Indigenous Council, Linda Burney, says Ryan's decision not to apologise is unacceptable.

"He does not understand ... the insult he has caused," she said.

"The day has passed when you can get away with saying, 'oh, I didn't mean any offence so therefore I don't have to apologise' ... It's completely unacceptable."

Morrow, who has called rugby league for the ABC since 1980, is being investigated for his role in the incident.